Project Summary/Abstract An estimated 40% of women who smoke quit during their pregnancy, however, up to 80% of these women relapse in the postpartum period, despite the health risks for themselves and their children. Relapse prevention in the postpartum period offers a unique opportunity to capitalize on a positive behavioral change. Yet, the design of effective smoking interventions for postpartum relapse prevention is challenging, due in large part to the competing needs and stressors in this population, especially among low income women. New, innovative intervention delivery models are needed to provide high levels of social support for ongoing behavioral change, while simultaneously addressing the new demands associated with young babies. Twitter, one of the most popular microblogging social media platforms that facilitate an instant mode of communication via tweets (short texts), seems especially promising for delivering smoking cessation interventions among underserved populations. Guided by the Cognitive-Social Health Information Processing (C-SHIP) framework, as well as by health communication best practices, the proposed study will develop and test an evidence- based, cognitive-behavioral twitter-enabled system-generated and participant-driven intervention (Tweet2commit) designed to reduce postpartum smoking relapse among low-income minority women who have quit immediately before or during their pregnancies. The Tweet2commit will be developed through a systematic formative evaluation process that includes literature and evidence-based content review, followed by an iterative cycling of text drafting, health literacy evaluation of texts, review by targeted focus group and pre-test through usability testing. The overarching goal of Tweet2commit is to provide evidence-based information and cognitive-behavioral coping strategies, as well as to harness the potential of peer-mediated social interaction, for supporting smoking abstinence. The intervention will consist of: 1) system-generated tweets targeting C-SHIP-based relapse factors and 2) user-generated tweets: participants will be asked to tweet when commenting on the system-generated tweets or when experiencing needs for coping with lapse or relapse so their peer can respond accordingly. We will also use a combination of best practice strategies to engage online participation and peer-support exchange. A pilot RCT will be conducted to explore the efficacy of the Tweet2commit intervention on reducing postpartum relapse rates, compared to a Usual Care control. A mixed-methods approach including the analysis of objective Twitter usage data will be conducted to measure participant?s engagement and satisfaction as well as perceived barriers. The proposed research will be the first randomized controlled study that leverages the potential of Twitter for disseminating evidence-based smoking cessation strategies and harnessing the participatory nature of tweeting for live interactive mobile support groups among underserved postpartum women. The approach is innovative, evidence-based, highly transportable for wide scale dissemination, and can readily be applied to other substance abuse contexts.